Using magnetic tape for storing duplicate copies of hard disk files. Starting in the 1980s, internal and external tape drives were occasionally used with personal computers. By the late 1990s, personal computer tape backup was largely abandoned due to CD-ROMs and the Internet. Not So For Large Backup Systems Large tape backup systems within the enterprise have always been used and continue to survive as a complementary disk backup (see HSM). Disk advantages are: fewer read errors; fast access to data; and random access capability that enables deduplication (storing only changes). However, tape offers several advantages over disk. They are less costly per byte of storage and are infinitely scalable by merely adding cartridges. They also enable transportability for off-site backup. See deduplication, magnetic tape and storage virtualization.